Plywood planked dory

Discussion in 'Wooden Boat Building and Restoration' started by Sunburned One, Jan 20, 2021.

  1. DCockey
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    DCockey Senior Member

    Only if you have a substantial amount of glass along the chine.
    That could be a challenge with lapstrake planking.
     
  2. wet feet
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    wet feet Senior Member

    For reference the OK's I referred to in my previous post were built with a single strip of 2 " tape inside and the same outside, as are the boats in the attached files.If the boat is to be glassed outside and inside,I would knock off the lands on the outside and turn them into a chine type joint.It would make the glassing a huge amount easier.
     

    Attached Files:

  3. Sunburned One
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    Sunburned One Junior Member

    This is all great news. I was worried from the tone of the initial responses that I was missing something. I felt Gerr’s scantling rules were a great resource for reverse engineering craft built similarly to what I wanted to do, so I didn’t think I was heading too far astray. I kind of figured the numbers weren’t perfect but that worst case if I err on the heavy side of the glassing schedule I still end up with a serviceable craft and less maintenance to boot, which is important to me as well.
    I’m think I’m going to build this thing as planned then, upside down with the ease of stitch and glue construction on the chines but with the added fun and structural benefit that glued lapstrake construction offers. I’ll have to make up some strake clamps of some type. I guess it will be sort of a hybrid of old and new then. Now, one final question and then I’m off to the races. With material this thin should I even bother beveling the laps? I figure they might function as “superchines” in the unbeveled state. Plus the glassing won’t blur out the lapstrake look as it might otherwise. Opinions? Is it too heretical?
     
  4. wet feet
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    wet feet Senior Member

    CLC call that "lapstitch" and yes it can be done.It also makes glassing over the very large laps quite interesting,but with the width of the land I suppose a good radius would be possible.
     
  5. messabout
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    messabout Senior Member

    There are plenty, more than plenty, readily available plans for boats of that size. Why bother with an antiquated design whose scantlings are appropriate for a small warship? Even old time Ian Oughtbred designs for small lapstrake dinghys use 6mm ply

    Take a look at some of the glued lap designs by other, more modern designers. CLC, for example, have lap strake designs that use Ocumee as thin as 4mm in places. few if any of their boats have failed because of structural inadequacies. If cartopping is your aim then light weight is of considerable concern.
     
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  6. DCockey
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    DCockey Senior Member

    The angles between planks on the Chamberlain dory skiff at relatively small. One possibility would be to not bevel the laps and fill the resulting gap with epoxy and filler mix, though that could get messy. Beveling is not difficult with a sharp plane. Being able to sharpen a plane blade is an essential skill.

    With lapstrake construction you will need to cut the gains in the laps at the stem. Gains can be cut at the transom or the transom can be notched.

    Screws can be used as temporarily to pull laps together until the expoxy sets. Then remove the screws and fill the holes. If the planks will be painted the filled screw holes will vanish after painting. If the planks will be varnished the filled screw holes will remain visible.
     
  7. Sunburned One
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    Sunburned One Junior Member

    I suppose that I've always liked the the look of these dories and always wanted to build one. I already had the Gardner book. Also, not to disparage the work of many talented designers, but I guess when I look at new boat designs I still feel like I am seeing the old designs reimagined in new ways using newer materials and techniques. That's not a criticism per se, just my view.
    I am trying to satisfy a lot of wants here and not all will be met with 100% success. Life is compromise. But one of the most important of these wants is to learn from every aspect of this process. By taking this old design and trying to make it into something a bit different I would argue that I am learning a whole lot more than I would by purchasing a design that, while perfectly suitable and perhaps "better", won't really teach me as much as reimagining this old tub from the bottom up. In this there is the ever present risk of failure to some degree, but its very exciting this way wouldn't you say?
    All of these wonderful responses to my questions has only reinforced the fact that this will probably work out just fine. I can build this thing as heavy or as light as I want. I even contemplated skin on frame for a time, but sooner or later you've got to take all of these compromises and decide on something or it will never float. I've never spiled a plank, but I know I can. I live in Louisville, Kentucky for heaven's sake. I have to keep my spirits up somehow.
     
  8. Sunburned One
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    Sunburned One Junior Member

    I'm a woodworker by trade so my plane irons are as sharp as my partner's tongue when she is displeased with me. I do not fear the lap bevels. I am just debating their necessity here. I guess the gains are as good a reason to bevel as any. I usually build furniture that no one wants. Now I will try to build a boat that no one does ;-) Thanks to all of you who have given me much to chew on. I do appreciate it. Crab Spider Table.jpg
     
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  9. wet feet
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    wet feet Senior Member

    From the look of that piece you won't have any difficulty dealing with curves,people with a background in other forms of woodworking often do.I suggest you try glassing a sample piece of a lapped joint before committing to the real thing to get a feel for the process.As has been said the design is rather traditional and could be built lighter with modern materials but that might be a policy better saved for the next boat.
     
  10. Sunburned One
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    Sunburned One Junior Member

    I will do some testing before I fully commit to anything. From the discussion so far there appear to be many ways to skin this cat.
     
  11. rangebowdrie
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    rangebowdrie Junior Member

    Back in the old days Chris Craft had a whole line up of boats called "Sea Skiffs".
    They had plywood bottoms and lapstrake plywood sides,, few survive today.
    Today, excepting for a certain "look", their is little to recommend it over sheet plywood, and if the hull is to
    be glassed the effort involved in glassing and fairing the ridges of the laps is over the top.
    Lapstrake lives on in fiberglass where a boat comes out of a mold, and in that case can offer a little more rigidity to the structure.
    That style/type of construction also adds wetted surface and drag,, why bother with it.
     
  12. bajansailor
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    bajansailor Marine Surveyor

  13. rangebowdrie
    Joined: Nov 2009
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    rangebowdrie Junior Member

    Interesting that you posted this/that.
    Had a conversation just a couple of days ago with a fellow who is quite knowledgeable, and is in the business of restoring old wooden runabouts/small cruisers,, generally in the 18>22 ft. range, ones that you could trailer.
    He was telling me that for a short period of time Lyman was furnishing some lapstrake "Sea Skiff" and "Cavalier" hulls to Chris Craft.
    Chris Craft would install their own engines/trim/furnishings/etc., and sell them as Chris Crafts.
    I can't speak to the accuracy of that, but it wouldn't surprise me.
     
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  14. bajansailor
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    bajansailor Marine Surveyor

    That sounds very plausible, re Lyman supplying basic lapstrake hulls to Chris Craft - the Lyman folk appeared to have a real production line going (relatively!).
     
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  15. Sunburned One
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    Sunburned One Junior Member

    I agree with your point about the prospect of fairing in the laps if they are glassed over. It will be a pain I am sure. As for wetted surface and drag, while you are indeed correct I can’t see how it matters much in this case. A displacement hull this short will be slow no matter what the wetted surface. It’s just a row boat. If I had the space to store something long and sleek then I would be looking for something entirely different. A sharpie perhaps.
    I do admit I like the look. I also like the idea of being able to use it off the beach on those occasions when I get to hit the coast. As a multi-use hull form it suits my purposes well and it’s got enough rocker that if I make the skeg removable it will work well as a drifter on the bigger rivers here. I don’t expect it would suit everyone the same as me.
     
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